Hong Kong’s top court gave three jailed student leaders of the 2014 Occupy campaign the go-ahead on Tuesday to appeal against their sentences for an illegal protest, after judges agreed the case involved important legal points on civil disobedience in the city.

The Court of Final Appeal allowed Joshua Wong Chi-fung, 21, and Nathan Law Kwun-chung, 24 – whom it had earlier granted bail – along with Alex Chow Yong-kang, 27, to lodge their appeals after their initial non-custodial sentences were replaced with jail terms.

The appeal will be heard on January 16, centring on legal uncertainties the trio’s lawyers argued had arisen from their case, such as how much weight courts should place on defendants’ good intentions when sentencing them for civil disobedience.

Chief Justice Geoffrey Ma Tao-li said some of these legal questions touched on issues of “substantial and grave injustice” and laws of “great and general importance” – the two thresholds for granting permission to appeal.

He, along with fellow judges Roberto Ribeiro and Robert Tang Kwok-ching, also granted Chow bail, which allowed him to reunite with the other two outside court for the first time since they were jailed in August for unlawful assembly.

Their crime was the storming of the government headquarters compound at Tamar in September 2014, which effectively triggered the 79-day occupation of roads by protesters demanding greater democracy.

“I am very confident,” Chow said, looking forward to the appeal.

The trio stood shoulder to shoulder outside court. “There is the same familiar feeling,” Law said. “We’re still ourselves, persisting in our beliefs.”

Wong said a statement issued earlier to support them by the UN’s special rapporteurs on the right to freedom of opinion and expression, and the situation of human rights defenders, showed that the world had been paying attention to their case.

The appeal is expected to have implications for the dynamic between criminal justice and constitutional rights in Hong Kong, as part of it will concern the extent to which a protester, if convicted of a crime, can have his or her motive for civil disobedience taken into consideration during sentencing. Justice Ma said the top court would like to hear lawyers’ views on four issues, one of which in particular concerned civil disobedience and constitutional rights.

To what extent should civil disobedience be considered a factor when a crime was committed in its name, he asked.

After the Court of Appeal ruling to jail the trio, critics and legal experts expressed concern about how much the appellate court, which normally only addresses legal issues, was allowed to alter factual findings of a lower court.

While the sentencing magistrate concluded that the storming of the government compound had not been violent, the appeal judges revisited video footage and found that it involved a high risk of violence.

Ma said the top justices would like to hear arguments on the extent to which the appeal court was allowed to “reverse, modify, substitute and supplement” factual findings from a lower court.

And given that the appeal court had taken the opportunity to issue a new sentencing guideline with the trio, Ma added, another question was whether it was right for them to be sentenced accordingly.

He said his remaining point concerned whether it was appropriate for the Court of Appeal to sentence Wong, who was 20 at the time, without calling for reports to study other sentencing options, such as sending him to a training centre.

Wong and Law were originally given community service orders, and Chow a suspended jail sentence, but the Court of Appeal granted a review of the penalties in August at the request of prosecutors seeking stiffer punishment for them. Wong, Chow and Law were eventually sentenced to six, seven and eight months in jail, respectively.